It is an early season Amanita that is associated with hemlock. The darker disc on a yellow cap is one important character, the ragged limbs sticking up from a very white bulb is another, the quick loss of the ring (annulus, partial veil) is another. The species has rather round spores which is an important microscopic character. It is thought to belong in the gemmatoid group of species in Amanita section Amanita. I think the name applies to your other observations posted on the same day that have yellow caps and the other (above cited) characters.